Nuclear Theory·nucl-th

Friday·July 8, 2016

12 papers—5 primary·7 cross-listed

06
Resonance decay effect on conserved number fluctuations in a hadron resonance gas model
D. K. Mishra🇮🇳 · P. Garg🇺🇸 · P. K. Netrakanti🇮🇳 · A. K. Mohanty🇮🇳
We study the effect of charged secondaries coming from resonance decay on the net-baryon, net-charge and net-strangeness fluctuations in high energy heavy-ion collisions within the hadron resonance gas (HRG) model. We emphasize the importance of including weak decays along with other resonance decays in the HRG, while comparing with the experimental observables. The effect of kinematic cuts on resonances and primordial particles on the conserved number fluctuations are also studied. The HRG model calculations with the inclusion of resonance decays and kinematical cuts are compared with the recent experimental data from STAR and PHENIX experiments. We find a good agreement between our model calculations and the experimental measurements for both net-proton and net-charge distributions.
↳ hep-phnucl-exnucl-thPRC(2016)·31 citations
07
Generalized weak-binding relations of compositeness in effective field theory
Yuki Kamiya🇯🇵 · Tetsuo Hyodo🇯🇵
We study the compositeness of near-threshold states to investigate the internal structure of exotic hadron candidates. Within the framework of effective field theory, Weinberg's weak-binding relation is extended to more general cases by easing several preconditions. First, by evaluating the contribution from the decay channel, we obtain the generalized relation for unstable quasibound states. Next, we generalize the relation to include the nearby CDD (Castillejo-Dalitz-Dyson) pole contribution with the help of the Pade approximant. The validity of the estimation with the generalized weak-binding relations is examined by numerical calculations. The method to systematically evaluate the error in the weak-binding relation is presented. Finally, by applying the extended relation to Lambda(1405), f0(980) and a0(980), we discuss their internal structure, in comparison with other approaches.
↳ hep-phnucl-thPTEP(2017)·53 citations
08
Probing Transverse Momentum Broadening via Dihadron and Hadron-jet Angular Correlations in Relativistic Heavy-ion Collisions
Lin Chen🇨🇳 · Guang-You Qin🇨🇳 · Shu-Yi Wei🇨🇳 · Bo-Wen Xiao🇨🇳 · Han-Zhong Zhang🇨🇳
Dijet, dihadron, hadron-jet angular correlations have been reckoned as important probes of the transverse momentum broadening effects in relativistic nuclear collisions. When a pair of high-energy jets created in hard collisions traverse the quark-gluon plasma produced in heavy-ion collisions, they become de-correlated due to the vacuum soft gluon radiation associated with the Sudakov logarithms and the medium-induced transverse momentum broadening. For the first time, we employ the systematical resummation formalism and establish a baseline calculation to describe the dihadron and hadron-jet angular correlation data in $pp$ and peripheral $AA$ collisions where the medium effect is negligible. We demonstrate that the medium-induced broadening $⟨ p_{⊥}^{2} ⟩$ and the so-called jet quenching parameter $q^$ can be extracted from the angular de-correlations observed in $AA$ collisions. A global $χ^{2}$ analysis of dihadron and hadron-jet angular correlation data renders the best fit $⟨ p_{⊥}^{2} ⟩ \sim 13 GeV^{2}$ for a quark jet at RHIC top energy. Further experimental and theoretical efforts along the direction of this work shall significantly advance the quantitative understanding of transverse momentum broadening and help us acquire unprecedented knowledge of jet quenching parameter in relativistic heavy-ion collisions.
↳ hep-phnucl-exnucl-thPLB(2017)·91 citations
09
Systematic Comparison of Tsallis Statistics for Charged Pions Produced In $pp$ Collisions
A.S. Parvan🇷🇺 · O.V. Teryaev🇷🇺 · J. Cleymans🇿🇦
The energy dependence of Tsallis statistics parameters is presented for charged pions produced at beam energies ranging between 6.3 GeV and 7 TeV. It is found that deviations from Boltzmann statistics are monotonically growing with beam energy. This may be attributed to the dominance of low $x$ at higher energies leading to the power-like NLO QCD spectra for which Tsallis statistics may serve as effective theory. At the same time, for larger $x$ at lower beam energies the Gaussian falloff of transverse-momentum-dependent distributions is crucial and correspondent effective description is provided by the Boltzmann distribution.
↳ nucl-thhep-phEPJA(2017)·48 citations
10
On the structure observed in the in-flight $^{3} He (K^{-}, Λ p) n$ reaction at J-PARC
Takayasu Sekihara (JAEA, Ibaraki)🇯🇵 · Eulogio Oset (Valencia U. amd Valencia U., IFIC)🇪🇸 · Angels Ramos (Barcelona U. and ICC, Barcelona U.)🇪🇸
A theoretical investigation is done to clarify the origin of the peak structure observed near the $K^{-} pp$ threshold in the in-flight $^{3} He (K^{-}, Λ p) n$ reaction of the J-PARC E15 experiment, which could be a signal of the lightest kaonic nuclei, that is, the $K ˉ N N (I = 1/2)$ state. For the investigation, we evaluate the $Λ p$ invariant mass spectrum assuming two possible scenarios to interpret the experimental peak. One assumes that the $Λ (1405)$ resonance is generated after the emission of an energetic neutron from the absorption of the initial $K^{-}$ , not forming a bound state with the remaining proton. This uncorrelated $Λ (1405) p$ system subsequently decays into the final $Λ p$ . The other scenario implies that, after the emission of the energetic neutron, a $K ˉ N N$ bound state is formed, decaying eventually into a $Λ p$ pair. Our results show that the experimental signal observed in the in-flight $^{3} He (K^{-}, Λ p) n$ reaction at J-PARC is qualitatively well reproduced by the assumption that a $K ˉ N N$ bound state is generated in the reaction, definitely discarding the interpretation in terms of an uncorrelated $Λ (1405) p$ state.
↳ hep-phnucl-exnucl-thPTEP(2016)·58 citations
11
Testing the running coupling $k_{T}$ -factorization formula for the inclusive gluon production
F.O. Durães🇧🇷 · A.V. Giannini🇧🇷 · V.P. Goncalves🇸🇪 · F.S. Navarra🇧🇷
The inclusive gluon production at midrapidities is described in the Color Glass Condensate formalism using the $k_{T}$ - factorization formula, which was derived at fixed coupling constant considering the scattering of a dilute system of partons with a dense one. Recent analysis demonstrated that this approach provides a satisfactory description of the experimental data for the inclusive hadron production in $pp / p A / AA$ collisions. However, these studies are based on the fixed coupling $k_{T}$ - factorization formula, which does not take into account the running coupling corrections, which are important to set the scales present in the cross section. In this paper we consider the running coupling corrected $k_{T}$ - factorization formula conjectured some years ago and investigate the impact of the running coupling corrections on the observables. In particular, the pseudorapidity distributions and charged hadrons multiplicity are calculated considering $pp$ , $d A u / pP b$ and $A u A u / P b P b$ collisions at RHIC and LHC energies. We compare the corrected running coupling predictions with those obtained using the original $k_{T}$ - factorization assuming a fixed coupling or a prescription for the inclusion of the running of the coupling. Considering the Kharzeev - Levin - Nardi unintegrated gluon distribution and a simplified model for the nuclear geometry, we demonstrate that the distinct predictions are similar for the pseudorapidity distributions in $pp / p A / AA$ collisions and for the charged hadrons multiplicity in $pp / p A$ collisions. On the other hand, the running coupling corrected $k_{T}$ - factorization formula predicts a smoother energy dependence for $d N / d η$ in $AA$ collisions.
↳ hep-phhep-exnucl-exnucl-thPRD(2016)·17 citations
12
Looking for bound states and resonances in the $η^{'} K K ˉ$ system
A. Martínez Torres🇧🇷 · K. P. Khemchandani🇧🇷
Motivated by the continuous experimental investigations of $X (1835)$ in three-body decay channels like $η^{'} π^{+} π^{-}$ , we investigate the $η^{'} K K ˉ$ system with the aim of searching for bound states and/or resonances when the dynamics involved in the $K K ˉ$ subsystem can form the resonances: $f_{0} (980)$ in isospin 0 or $a_{0} (980)$ in isospin 1. For this, we solve the Faddeev equations for the three-body system. The input two-body $t$ -matrices are obtained by solving Bethe-Salpeter equations in a coupled channel formalism. As a result, no signal of a three-body bound state or resonance is found.
↳ hep-phnucl-thPRD(2016)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE

Resonance decay effect on conserved number fluctuations in a hadron resonance gas model

Generalized weak-binding relations of compositeness in effective field theory

Probing Transverse Momentum Broadening via Dihadron and Hadron-jet Angular Correlations in Relativistic Heavy-ion Collisions

Systematic Comparison of Tsallis Statistics for Charged Pions Produced In pp Collisions

On the structure observed in the in-flight 3He(K−,Λp)n reaction at J-PARC

Testing the running coupling kT​-factorization formula for the inclusive gluon production

Looking for bound states and resonances in the η′KKˉ system

Affiliations

Systematic Comparison of Tsallis Statistics for Charged Pions Produced In $pp$ Collisions

On the structure observed in the in-flight $^{3} He (K^{-}, Λ p) n$ reaction at J-PARC

Testing the running coupling $k_{T}$ -factorization formula for the inclusive gluon production

Looking for bound states and resonances in the $η^{'} K K ˉ$ system